Method of manufacturing sgt devices
Patent Information
- Application Number
- CN202610923825.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-06-24
- Publication Date
- 2026-10-16
AI Technical Summary
[0004]然而，发明人在研究中发现，上述工艺流程存在明显缺陷：预清洗步骤中使用的药液对晶圆边缘的冲洗作用会使得晶圆侧壁上的镀层结合力变差，产生剥离（peeling）现象（参见图1），从而影响产品良率和正常生产流片
[0020] This application first removes the back seal layer on the back side of the substrate through pre-cleaning, then forms a first protective film on the back side of the substrate, followed by electroless plating to form a metal plating layer on the front side of the substrate. After removing the first protective film, back-side thinning is performed. Thus, on the one hand, pre-cleaning is completed before the front-side plating layer is formed, avoiding the pre-cleaning solution from scouring the edges of the already deposited substrate and eliminating the problem of plating peeling off the substrate edge sidewalls. On the other hand, the first protective film provides physical isolation during the electroless plating process, effectively preventing plating on the back side of the substrate and ensuring the cleanliness of the back side. This application solves the defect of mutual constraints between the pre-cleaning and electroless plating processes in the SGT device manufacturing process of related technologies without changing the electroless plating solution formula or adding complex equipment modifications, which is beneficial to improving product yield and ensuring normal production tape-out.
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Figure CN122934877A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of semiconductor devices and integrated circuit technology, and in particular to a method for manufacturing an SGT device. Background Technology
[0002] Shielded Gate Trench MOSFETs (SGTs) are important devices in the field of power semiconductors and are widely used in medium and low voltage power management, battery protection, and motor drives.
[0003] In the manufacturing process of SGT devices provided by related technologies, taking a 100V SGT device as an example, to improve product stress, a relatively thick oxide layer is usually deposited on the back side of the wafer as a back seal layer. Although this back seal layer helps to alleviate stress, it can cause excessive load and machine alarms during subsequent back-side thinning and mechanical polishing. Therefore, a pre-cleaning process must be added before the back-side thinning process to remove it. At the same time, to keep the back side of the wafer clean and avoid back-side contamination affecting the quality of subsequent thinning and back-side metallization, the back side must be protected from plating during electroless plating. Since the back seal layer has a natural inertness to the electroless plating solution, the typical process flow is as follows: after completing the front-side process, electroless plating is performed directly, using the wafer back seal layer as a barrier to prevent plating on the back side. Then, pre-cleaning is performed to remove the back seal layer, and finally, front-side lamination and back-side thinning are performed sequentially.
[0004] However, the inventors discovered a significant flaw in the above process flow during their research: the rinsing effect of the chemical solution used in the pre-cleaning step on the wafer edges weakens the adhesion of the plating layer on the wafer sidewalls, resulting in peeling (see...). Figure 1 This can affect product yield and normal production tape-out. Summary of the Invention
[0005] This application provides a method for manufacturing an SGT device that avoids the scouring of the deposited coating by the pre-cleaning solution at the edge of the substrate, thereby eliminating the problem of coating peeling off the sidewalls of the substrate edge.
[0006] In view of this, this application provides a method for manufacturing an SGT device, comprising:
[0007] S1, a substrate is provided, and a back sealing layer is formed on the back side of the substrate to form the front structure of the SGT device;
[0008] S2, pre-cleaning is performed, and the back seal layer is removed;
[0009] S3, a first protective film is formed on the back side of the substrate;
[0010] S4, perform chemical plating to form a coating on the front side and sidewalls of the substrate. After the chemical plating, the first protective film is removed.
[0011] S5, mechanical grinding is performed, and the back side of the substrate is thinned.
[0012] Optionally, before performing step S5, a step of forming a second protective film on the front side of the substrate is also included.
[0013] Optionally, the diameter of the first protective film matches the diameter of the substrate.
[0014] Optionally, the diameter of the first protective film is smaller than the diameter of the substrate, so that the edge of the first protective film is recessed by 0.5-1 mm relative to the edge of the substrate.
[0015] Optionally, the diameter of the first protective film is 299mm-300mm, and the diameter of the substrate is 300mm.
[0016] Optionally, the first protective film is a protective film that can withstand the corrosion of the electroless plating solution.
[0017] Optionally, the breakdown voltage of the SGT device is 100V.
[0018] Optionally, the initial thickness of the substrate before the back seal layer is formed is 700-800 μm.
[0019] The technical solution of this application has at least the following advantages:
[0020] This application first removes the back seal layer on the back side of the substrate through pre-cleaning, then forms a first protective film on the back side of the substrate, followed by electroless plating to form a metal plating layer on the front side of the substrate. After removing the first protective film, back-side thinning is performed. Thus, on the one hand, pre-cleaning is completed before the front-side plating layer is formed, avoiding the pre-cleaning solution from scouring the edges of the already deposited substrate and eliminating the problem of plating peeling off the substrate edge sidewalls. On the other hand, the first protective film provides physical isolation during the electroless plating process, effectively preventing plating on the back side of the substrate and ensuring the cleanliness of the back side. This application solves the defect of mutual constraints between the pre-cleaning and electroless plating processes in the SGT device manufacturing process of related technologies without changing the electroless plating solution formula or adding complex equipment modifications, which is beneficial to improving product yield and ensuring normal production tape-out. Attached Figure Description
[0021] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0022] Figure 1 These are photos of the wafer sidewalls after chemical plating followed by pre-cleaning, as described in related technologies.
[0023] Figure 2 This is a process flow diagram of a method for manufacturing an SGT device provided in an exemplary embodiment of this application;
[0024] Figure 3 This is a photograph of the back side of the substrate after chemical plating in a method for manufacturing an SGT device according to an exemplary embodiment of this application;
[0025] Figure 4 This is a photograph of the substrate sidewall after chemical plating in a method for manufacturing an SGT device according to an exemplary embodiment of this application;
[0026] Figure 5 This is a photograph of the back side of the substrate after chemical plating in a manufacturing method of an SGT device provided as an exemplary comparative example of this application. Detailed Implementation
[0027] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0028] In the description of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.
[0029] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components; and they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.
[0030] Furthermore, the technical features involved in the different embodiments of this application described below can be combined with each other as long as they do not conflict with each other.
[0031] The following is combined Figures 1 to 5 This describes an embodiment of the present application.
[0032] refer to Figure 1 The illustration shows an embodiment of this application, providing a method for manufacturing an SGT device, comprising:
[0033] S1 provides a substrate, on the back side of which a back sealing layer is formed to form the front structure of the SGT device.
[0034] Exemplarily, the substrate can be a silicon substrate, a germanium (Ge) substrate, a gallium arsenide (GaAs) substrate, or other substrates suitable for manufacturing SGT semiconductor devices. The substrate includes a front side, a back side opposite the front side, and sidewalls connecting the front and back sides. A deposition process, such as chemical vapor deposition (CVD), can be used to deposit an oxide layer, such as silicon oxide (SiO2), on the back side of the substrate to form a back seal layer that helps to balance the stress introduced by the front side process.
[0035] For example, the front-side structure of an SGT device can be formed using a front-side process, which includes a trench, a shielding gate, a gate, a source region, a body region, and a front-side metal layer. Since this part is prior art, the embodiments of this application will not elaborate further on it.
[0036] In some embodiments, the initial thickness of the substrate before the back seal layer is formed is 700-800 μm.
[0037] For example, the initial thickness of the substrate before the back seal layer is formed can be 700 μm, 750 μm, 800 μm, etc.
[0038] In some embodiments, the breakdown voltage of the SGT device is 100V.
[0039] S2, pre-cleaning is performed, and the back seal layer is removed.
[0040] For example, a wet etching process can be used to pre-clean the back side of the substrate to completely remove the back seal layer. After the back seal layer is removed, the back side of the substrate is exposed.
[0041] S3, a first protective film is formed on the back side of the substrate.
[0042] For example, a first protective film can be formed on the back side of the substrate using a lamination process. This first protective film is a protective film that can withstand corrosion from chemical plating solutions, such as a polyimide (PI) film, a polytetrafluoroethylene (PTFE) film, or other materials that are resistant to acids, alkalis, and high temperatures.
[0043] In some embodiments, the diameter of the first protective film matches the diameter of the substrate.
[0044] For example, the diameter of the first protective film is 300 mm, and the diameter of the substrate is 300 mm.
[0045] In some embodiments, a first protective film covers the back side of the substrate, has a diameter smaller than that of the substrate, and has its edges recessed 0.5-1 mm relative to the edges of the substrate to expose an annular region at the back edge of the substrate.
[0046] This inward-shrinking design utilizes the exposed back edge of the substrate to guide the continuous coating over the substrate sidewalls, forming a C-shaped coating structure of front coating - sidewall coating - back edge coating. This enhances the adhesion of the coating to the substrate sidewalls and effectively inhibits coating edge peeling. Furthermore, precise control of the inward-shrinking distance, combined with the physical isolation of the core area on the back side of the substrate (i.e., the back area excluding the annular area at the back edge) by the first protective film, prevents the chemical plating solution from penetrating into the core area, thus ensuring the cleanliness of the core area and preventing adverse effects on subsequent back-side thinning and back-golding processes. In addition, this inward-shrinking design creates a clear step at the edge of the back side of the substrate, facilitating the removal of the first protective film.
[0047] For example, the diameter of the first protective film is 299 mm, the diameter of the substrate is 300 mm, and the edge of the first protective film is recessed by 1 mm relative to the edge of the substrate.
[0048] For example, the diameter of the first protective film is 299.5 mm, the diameter of the substrate is 300 mm, and the edge of the first protective film is recessed by 0.5 mm relative to the edge of the substrate.
[0049] S4, perform electroless plating to form a coating on the front and sidewalls of the substrate. After electroless plating, the first protective film is removed.
[0050] For example, a chemical plating process can be used to deposit metal plating layers on the front side and sidewalls of the substrate. After the chemical plating is completed, the first protective film covering the back side of the substrate can be removed by mechanical peeling.
[0051] S5, mechanical polishing is performed, and the back side of the substrate is thinned.
[0052] In some embodiments, before performing step S5, a step of forming a second protective film on the front side of the substrate is further included.
[0053] For example, after removing the first protective film, a second protective film is attached to the front side of the substrate, and then the back side of the substrate is mechanically ground to thin the substrate to the target thickness. The second protective film can be made of UV-curable tape, heat-release tape, etc.
[0054] In the manufacturing process of SGT devices provided by related technologies, taking a 100V SGT device as an example, to improve product stress, a relatively thick oxide layer is usually deposited on the back side of the wafer as a back seal layer. Although this back seal layer helps to alleviate stress, it can cause excessive load and machine alarms during subsequent back-side thinning and mechanical polishing. Therefore, a pre-cleaning process must be added before the back-side thinning process to remove it. At the same time, to keep the back side of the wafer clean and avoid back-side contamination affecting the quality of subsequent thinning and back-side metallization, the back side must be protected from plating during electroless plating. Since the back seal layer has a natural inertness to the electroless plating solution, the typical process flow is as follows: after completing the front-side process, electroless plating is performed directly, using the wafer back seal layer as a barrier to prevent plating on the back side. Then, pre-cleaning is performed to remove the back seal layer, and finally, front-side lamination and back-side thinning are performed sequentially. However, the inventors discovered a significant flaw in the above process flow during their research: the rinsing effect of the chemical solution used in the pre-cleaning step on the wafer edges weakens the adhesion of the plating layer on the wafer sidewalls, resulting in peeling (see...). Figure 1 This can affect product yield and normal production tape-out.
[0055] This application first removes the back seal layer on the back side of the substrate through pre-cleaning, then forms a first protective film on the back side of the substrate, followed by electroless plating to form a metal plating layer on the front side of the substrate. After removing the first protective film, back-side thinning is performed. Thus, on the one hand, pre-cleaning is completed before the front-side plating layer is formed, avoiding the pre-cleaning solution from scouring the edges of the already deposited substrate and eliminating the problem of plating peeling off the substrate edge sidewalls. On the other hand, the first protective film provides physical isolation during the electroless plating process, effectively preventing plating on the back side of the substrate and ensuring the cleanliness of the back side. This application solves the defect of mutual constraints between the pre-cleaning and electroless plating processes in the SGT device manufacturing process of related technologies without changing the electroless plating solution formula or adding complex equipment modifications, which is beneficial to improving product yield and ensuring normal production tape-out.
[0056] Example 1:
[0057] This embodiment provides a method for manufacturing an SGT device, including:
[0058] S1 provides a substrate, on the back side of which a back sealing layer is formed to form the front structure of the SGT device.
[0059] In this embodiment, the substrate is a silicon substrate with a diameter of 300 mm.
[0060] S2, pre-cleaning is performed, and the back seal layer is removed.
[0061] S3, a first protective film is formed on the back side of the substrate.
[0062] In this embodiment, the diameter of the first protective film is 300 mm.
[0063] In this embodiment, the first protective film is a polytetrafluoroethylene (PTFE) film.
[0064] S4, perform electroless plating to form a coating on the front and sidewalls of the substrate. After electroless plating, the first protective film is removed.
[0065] S5, a second protective film is formed on the front side of the substrate.
[0066] In this embodiment, the second protective film is made of UV-curable tape.
[0067] S6, mechanical polishing is performed, and the back side of the substrate is thinned.
[0068] Comparative Example 1:
[0069] The only difference between this comparative example and Example 1 is that step S3 is omitted, and there is no step of removing the first protective film after chemical plating in step S4.
[0070] Depend on Figure 3-4It can be seen that after chemical plating using the method of Example 1, there was no plating on the back side of the substrate and no peeling off from the substrate sidewalls. Figure 5 It can be seen that the back side of the substrate is plated after chemical plating using the method of Comparative Example 1.
[0071] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this application.
Claims
1. A method for manufacturing an SGT device, characterized in that, include: S1, a substrate is provided, and a back sealing layer is formed on the back side of the substrate to form the front structure of the SGT device; S2, pre-cleaning is performed, and the back seal layer is removed; S3, perform film application to form a first protective film on the back side of the substrate; S4, perform chemical plating to form a coating on the front side and sidewalls of the substrate. After the chemical plating, the first protective film is removed. S5, mechanical grinding is performed, and the back side of the substrate is thinned.
2. The method according to claim 1, characterized in that, Before performing step S5, a step of forming a second protective film on the front side of the substrate is also included.
3. The method according to claim 1, characterized in that, The diameter of the first protective film matches the diameter of the substrate.
4. The method according to claim 1, characterized in that, The diameter of the first protective film is smaller than the diameter of the substrate, so that the edge of the first protective film is recessed by 0.5-1 mm relative to the edge of the substrate.
5. The method according to claim 3 or 4, characterized in that, The diameter of the first protective film is 299mm-300mm, and the diameter of the substrate is 300mm.
6. The method according to claim 1, characterized in that, The first protective film is a protective film that can withstand the corrosion of the electroless plating solution.
7. The method according to claim 1, characterized in that, The breakdown voltage of the SGT device is 100V.
8. The method according to claim 1, characterized in that, The initial thickness of the substrate before the back seal layer is formed is 700-800 μm.